DISCUSSION OF WATEE AND VOLCANIC ACTIVITY 707 



WATER AND VOLCANIC ACTIVITY 1 

 BY ARTHUR L. DAY AND E. S. SHEPARD 



Published as pages 573-606 of this volume. 



Discussion 



The author replied to questions by W. M. Davis, R. A. Daly, J. F. Kemp, 

 and E. Howe as follows : 



(Davis.) Small but unmistakable pale blue flames of burning sulphur can 

 be seen at night during any period of considerable activity ; similarly a pale 

 blue flash following the explosion of a bubble, though with greater difficulty. 



(Daly.) The position of "Old Faithful" is somewhat variable when the banks 

 are falling in, following a receding lava column — perhaps due to partial choking 

 of the opening below. 



(Kemp.) Water above its critical temperature will circulate exactly like 

 any gas — percolate slowly through porous media, mix (or reach) with other 

 gases, etcetera. 



(Howe.) The bowl about the liquid lava, and in fact the entire island of 

 Hawaii, is porous and meteoric water falls on it. It is therefore not possible 

 to say that the lava has no meteoric water, but the probability of meteoric 

 water entering the lava near the surface is small. 



GEOLOGIC SECTION OF THE PANAMA CANAL ZONE 

 BY DONALD F. MAC DONALD 2 



(Abstract) 



Contents „ 



Page 



Rock succession of the Isthmus 707 



General statement 707 



Number 1. Bas Obispo formation 708 



Number 2. Las Cascades agglomerate 708 



Number 3. Bohio conglomerate 708 



Number 4. The Culebra formation . . . . 708 



Number 5. Cucuracha formation 709 



Number 6. Emperador limestone 709 



Number 7. Caimito formation 709 



Number 8. Panama formation 709 



Number 9. Gatun formation 709 



Number 10. Caribbean limestone : 710 



Number 11. Pleistocene formations 710 



Igneous rocks 710 



Rock Succession of the Isthmus. 



General Statement 



Within the Canal Zone are eleven distinct groups or formations of what may 

 broadly be designated as bedded rocks. There are also six broad rock groups 



1 Presented at the meeting under the title "Preliminary report of certain physical and 

 physlochemical observations at the Kilauea crater." 



2 Introduced by James F. Kemp. 



